Separation and analysis of restriction fragments by gel electrophoresis and Southern blotting are vital to the mapping of chromosomal DNA. At present, however, the information obtained from gels and blots is severely limited by the nonlinear response, limited dynamic range, low sensitivity and cumbersome processing inherent in the photographic methods used to record the distribution of fluorophore-stained or radionuclide-labeled DNA. This project will exploit recent advances in electronic imaging and computer technology that make possible accurate and rapid quantitation of the mass distribution of fluorophore-stained restriction fragments on gels and radionuclide-labeled probes on Southern blots. Computer programs for the storage and analysis of images of gels and blots will be developed to increase significantly the quality and quantity of information obtained while reducing the time required for data collection and processing.